1. Field of the Invention
The present invention relates to a recording liquid a (hereinafter referred to as ink) for performing record on recording media such as paper, plastic films, and the like by using an ink-jet recording system or a writing tool such as a fountain pen, felt pen, or the like.
2. Description of the Prior Art
The ink-jet recording system comprises forming ink droplets by any of various ink-discharging techniques and causing a portion or all of the droplets to deposit on a recording medium such as paper or the like to record an image thereon. Inks known and used for ink-jet recording systems are solutions or dispersions of various water-soluble dyes or pigments in liquid mediums such as water and mixtures thereof with water-soluble organic solvents.
Similar inks are also in use for recording with writing tools such as fountain pens, felt pens, and ball pens.
A variety of performance characteristics are naturally required for these inks. The most greatly required characteristic, is liquid stability so as not to form any precipitate that may clog a nozzle or an orifice of an ink-jet recorder or may deposit on a pen point during recording or at an intermission thereof for a short or long period. This characteristic is especially important to an ink-jet recording system wherein thermal energy is employed for discharging ink, since the temperature change therein tends to cause deposition of foreign matter on the surface of the heating heads However, inks of prior art: need incorporation of some additives in order to satisfy various requirements on the discharge characteristics, long-term storage stability, surface tension, and electrical properties of the ink, the distinctness and optical density of recorced images, etc. Moreover various impurities are contained in dyes used in prior art inks. Accordingly, these inks involve a number of difficulties such as clogging at nozzles or orifices of ink-jet recorders, deposit formation on the surface of the heating heads, and emergence of precipitates during prolonged storage of the inks. This is one of the reasons why inkjet recording systems has not come into wide use even with their many superior characteristics.